An encyclopedia is useful at which stage in the research process? after selecting a topic as a means of getting general information after formulating a thesis statement as a source from which to create note cards while evaluating and reworking the thesis based on note cards

The best answer is A) after selecting a topic as a means of getting general information

An encyclopedia entry, or Wikipedia article, is a great resource for getting general information on a topic. You probably won't be able to use to too extensively for citations or for an in-depth understanding of your topic, but you will get a broad survey which can help you to decide if you want to write about it and to have a general idea of it.